Communication over power lines has been proposed and used for remote metering. In typical systems for remote metering, a central controller communicates with a meter using a superimposed signal on the mains network. A meter sends an acknowledgement signal back to the central controller and may perform some function dependent on the message received.
Two well known problems that need to be overcome by power line communication systems are the noisy environment and potentially large signal attenuation. Various reading techniques and communication protocols have been developed to address these problems, for example using meters as digital relays to enable communication from the central controller to each of the meters. Examples of power line communication systems using signal repeaters are described in European patent publication No. 0 201 253 B1 and international patent publication no. WO 95/01030.
Advances in meter technology have provided improved functionality. For example, meters may communicate by a wireless link with other meters and with network controllers to perform various functions. An example of such a system is described in international patent publication no. WO 97/29466. A problem with such meters is the additional costing complexity resulting from the wireless communication. Also, as radio spectrum becomes increasingly in demand, the use of wireless communication from potentially millions of sources may not be commercially viable in many cases.
A mains network provides an extensive existing infra-structure. Further exploitation of the existing mains infra-structure would be advantageous. For example, increased functionality, both in terms of control and monitoring of the power network may be achieved, including improved metering and providing additional services to customers.
As a consequence of deregulation in the power supply industry in many countries, achieving reconciliation of power supplied and determining the power used and network losses has become a significant problem. The problem arises principally on the low voltage distribution network, where more than one retailer exists as well as a separate lines company. There is a need for improved measurement of network losses so that accuracy in power reconciliation can be improved.
It is thus an object of the present invention to provide a power line communication system and method that provides additional functionality for one or both of power network management and the provision of network services, or at least to provide the public with a useful alternative.